We reported previously that transfection of BL6 melanoma cells that do not express the α1,3-galactosyltransferase (α1,3GT) gene with the α1,3GT cDNA resulted in synthesis and expression of α-galactosyl epitopes (Galα1-3Galβ1-4GlcNAc-R) and an impairment of their metastatic potentials. It was of interest to test whether inhibition of metastatic properties of BL6 melanoma cells is specifically associated with the appearance of the terminal α-Gal or whether capping N-acetyllactosamine with another oligosaccharide would also affect the metastatic properties of BL6 melanoma cells. For this purpose, BL6-2 clone isolated from B16BL6 melanoma was transfected with the α1,2-fucosyltransferase (α1,2FT) cDNA. The α1,2FT catalyzes a transglycosylation reaction, resulting in syntheses of the Fucaα1-2Galβ1-4GlcNAc-R structure, which is known as the H antigen of O blood group in humans and is also synthesized in some cells of mice. Transfection of BL6 melanoma cells with the α1,2FT cDNA resulted in the appearance of the terminal Fucα1-2Galβ1-4GlcNAc-R epitopes reacting with the Ulex europaeus agglutinin lectin. In parallel, the transfected cells showed a decrease in N-acetyllactosamine sialylation. Decline in sialylation of the transfected cells is likely to be the result of competition between α1,2FT and α2,3- or α2,6-sialyltransferases for the common substrate N-acetyllactosamine (Galβ1-4GlcNAc-R) on N-linked carbohydrate chains of glycoproteins and glycolipids. The α1,2FT-transfected BL6-2 cells showed an increase in homotypic aggregation. In parallel, metastatic ability of the α1,2FT-transfected BL6-2 cells was reduced significantly in the immunocompetent as well as immunosuppressed (X-irradiated) mice. Thus, these data imply that capping N-acetyllactosamine with αGal or αFuc and the corresponding reduction in sialylation of BL6-2 melanoma cells were associated with reduction of their metastatic potential.

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This study is supported by NIH Grant CA59903.

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